Final answer:
The main functions of methylation and acetylation are to regulate gene transcription by changing the conformation of chromatin, which controls the accessibility of DNA. Acetylation typically unwinds DNA to promote transcription, while methylation can have varying effects. Drugs manipulating these modifications can affect gene expression patterns in cancer treatment.
Step-by-step explanation:
The main function of methylation and acetylation, along with other post-translational modifications (PTMs), is to regulate gene expression by altering chromatin conformation. These modifications affect how tightly or loosely DNA is wound around histone proteins, which in turn controls the accessibility of DNA to transcription machinery. For example, acetylation of histones typically makes the chromatin less condensed, allowing genes to be more readily transcribed. Conversely, methylation can either enhance or suppress transcription, depending on the context of where the methylation occurs on the histone proteins.
UV rays and other external stimuli can influence these modifications, leading to altered gene expression. Furthermore, new drugs that decrease DNA methylation and prevent the removal of histone acetyl groups help to maintain open chromatin conformation, thus promoting transcription of essential genes, such as housekeeping genes. These drugs hold therapeutic potential, particularly in the treatment of cancer, by keeping certain genes active that are necessary for normal cell function and repressing the expression of genes that contribute to tumorigenesis.